In a gas turbine engine, fuel is generally supplied to a combustor through a plurality of fuel nozzles in fluid communication with a fuel manifold. The fuel manifold receives fuel from one or more fuel inlet tubes.
Known inlet tubes generally have a single channel or two concentric channels, and the fuel is fed axially in each channel. The pressure of the axially fed fuel creates a considerable force along the axial direction of the tube which acts on the fuel manifold. This force is transferred to the support structure of the manifold, as well as the joints between the inlet tubes and the manifold, which can lead to a premature rupture thereof.
Since the combustor operates at high temperatures, engine fuel system components must be adequately protected against heat damage. Heat shields are often provided on the inlet tubes for such protection. However, heat shields can represent a significant weight increase for the fuel system.
Because of these high temperatures, a fuel leak could result in a fire. Thus, it is desirable that the fuel system be leak proof, and include a safe way to dispose of leaked fuel should a leak occur. A double walled construction is often used on inlet tubes and other conduits in order to provide an annular passageway for leaked fuel. Such a construction can also significantly increase the weight of the fuel system.
Accordingly, there is a need for a heat shielded fuel inlet tube that can provide for adequate disposition of leaked fuel while having a minimal weight.
There is also a need for a fuel inlet tube that can reduce the force transmitted along the axial direction of the tube to the manifold by fuel pressure.